765957-19-5Relevant academic research and scientific papers
Catalytic enantioselective synthesis of chiral 4-hydroxy 4′-substituted pyrazolones by the vinylogous aldol reaction of pyrazole-4,5-diones with 3-alkylidene-2-oxindoles
Hore, Soumyadip,Kumar, Krishna,Singh, Bhuvnesh,Singh, Ravi P
supporting information, p. 13747 - 13750 (2021/08/16)
Here, a bifunctional quinine-derived benzamide catalyzed direct enantioselective vinylogous aldol reaction between 3-alkylidene-2-oxindoles and pyrazole-4,5-diones has been developed. This challenging protocol has been achievedviathe H-bonding dual activation mode of the catalyst. Highly functional rich pyrazolone moieties having an oxindole core have been obtained with an excellentE/Z(>19?:?1), and high yields along with moderate enantioselectivity.
Asymmetric synthesis of atropisomeric pyrazole: Via an enantioselective reaction of azonaphthalene with pyrazolone
Yuan, Huijun,Li, Yao,Zhao, Hanhui,Yang, Zhihong,Li, Xin,Li, Wenjun
supporting information, p. 12715 - 12718 (2019/10/28)
The first catalytic asymmetric reaction of azonaphthalene with pyrazolone has been established. A wide range of axially chiral pyrazole derivatives have been achieved in good yields (68-99%) with excellent enantioselectivities (83-98% ee) by utilizing chiral phosphoric acid as a catalyst. This strategy provides an efficient and facile approach for the construction of axially chiral pyrazole derivatives. Theoretical calculations were carried out to elucidate the origins of enantioselectivity.
Asymmetric synthesis of spiropyrazolones through phosphine-catalyzed [4+1] annulation
Han, Xiaoyu,Yao, Weijun,Wang, Tianli,Tan, Yong Ren,Yan, Ziyu,Kwiatkowski, Jacek,Lu, Yixin
supporting information, p. 5643 - 5647 (2014/06/10)
An enantioselective synthesis of spiropyrazolones from allenoate-derived MBH acetates and pyrazolones through a phosphine-mediated [4+1] annulation process has been developed. Spiropyrazolones were readily prepared in good chemical yields and good to high enantioselectivities. This is the first asymmetric example in which α-substituted allenoates were utilized as a C4 synthon for phosphine-catalyzed [4+1] annulation. Optically enriched 4-spiro-5-pyrazolones were prepared through phosphine-catalyzed enantioselective [4+1] annulation. In this study, substituted pyrazolones were used as a C1 synthon in cycloaddition for the first time. Moreover, this is the first report in which α-substituted allenoates were utilized in an asymmetric [4+1] annulation.
